Establishing the sperm and seminal plasma mechanisms of paternal programming

我们成年后的健康状况可能会受到我们在子宫中发育的影响。母亲在怀孕期间饮食不佳会增加其后代超重的风险，成年后患2型糖尿病和心脏病。虽然母亲良好饮食的重要性是众所周知的，但父亲饮食的重要性却被忽视了。然而，对人类和动物的研究表明，如果父亲在受孕时饮食质量差（太多或太少），这不仅会影响他的精子质量，还会影响后代的长期心血管和代谢健康。动物研究在帮助我们了解父母的饮食如何影响后代健康方面发挥了重要作用。在这里，小鼠被证明特别有用，因为它们的繁殖和发育与人类相似。我们已经证明，给雄性小鼠喂食低蛋白饮食（LPD，营养不良）或高脂肪饮食（HFD，营养过剩）会影响睾丸内数百个基因的表达，加速胚胎发育速度并增加其大小怀孕期间的后代。重要的是，所有这些因素都与成年后肥胖、2型糖尿病和心脏病的风险增加有关。事实上，我们已经证明，喂食LPD的雄性小鼠的成年后代变得超重，并出现心脏病和2型糖尿病的症状。有趣的是，我们观察到精子和它们所携带的液体（精浆）都能够使后代健康不良。这些观察结果表明，父亲可以通过两种不同的方式影响后代的健康;第一种是通过精子中携带的信息，第二种是通过精浆。我们将在本项目中详细探讨这两种途径。我们有独特的优势，可以利用我们建立的小鼠LPD和HFD模型来确定父亲的饮食与其后代发育之间的联系机制。根据这一提议，我们将首先确定父亲的饮食如何影响其精子中传递的遗传信息。具体来说，我们将定义精子的RNA含量，已知这些分子会在受精后不久影响胚胎内的基因表达。我们还将研究这些RNA分子如何包装到精子中，因为它们在睾丸中发育和成熟。作为对这些研究的补充，我们将探索睾丸的细胞结构，以确定低质量的饮食如何影响它们制造精子的方式。我们的第二个目标是研究精浆的组成以及它如何与精子和母体生殖道相互作用。这些相互作用是重要的，因为精浆在精子离开睾丸后向精子添加额外的RNA分子，为精子受精做准备。此外，精浆在子宫内启动一系列免疫和炎症反应，为胚胎植入做好准备。因此，我们将研究精浆如何改变精子的RNA货物，以及它如何影响子宫内的蛋白质，免疫细胞和血管。在此之后，我们将研究子宫和胚胎之间的相互作用，看看它们的正常交流是否被不良的父亲饮食所破坏。最后，我们想了解一旦LPD和HFD男性被置于对照饮食中，精子和精浆恢复正常的速度有多快。这些研究对于告知不良饮食对男性生殖健康的影响可能有多持久很重要，这项工作在关注父亲饮食的作用方面是及时的。此外，我们对精浆和精子作用的关注意味着我们的研究也是新颖的。我们认为，了解父亲如何影响其后代的健康，对于告知男性如何提高成为父亲的机会以及对子女健康的益处至关重要。

Our health as an adult can be influenced by how we develop in the womb. Poor maternal diet during pregnancy can increase the risk her offspring will become overweight, have type 2 diabetes and heart disease as adults. While the importance of a good maternal diet is well understood, the importance of the father's diet has been overlooked. However, studies in humans and animals indicate that if the father eats a poor quality diet (too much or too little) at the time of conception, this not only affects the quality of his sperm, but can also affect the long-term cardiovascular and metabolic health of his offspring.Animal studies have played a significant role in helping us understand how parental diet may affect offspring health. Here, mice have proved especially informative as their reproduction and development are similar to humans. We have shown that feeding male mice either a low protein diet (LPD, under-nourished) or high fat diet (HFD, over-nourished) affects the expression of hundreds of genes within their testes, accelerates the rate their embryos develop and increases the size of their offspring during pregnancy. Importantly, all of these factors have been associated with increased risk of obesity, type 2 diabetes and heart disease in adult life. Indeed, we have shown that adult offspring from male mice fed LPD become over weight and developed symptoms of heart disease and type-2 diabetes. Interestingly, we observed that both the sperm and the fluid they are carried in (seminal plasma) were able to drive offspring ill-health. These observations suggest that a father can affect the health of his offspring in two separate ways; first through information carried in the sperm and second through the seminal plasma. It is these two pathways that we will explore in detail in this project. We are uniquely positioned to use our established mouse LPD and HFD models to define the mechanisms linking a father's diet with the development of his offspring.Under this proposal, we will first determine how a father's diet affects the genetic information passed on in his sperm. Specifically, we will define the sperm's RNA content, molecules known to influence gene expression within the embryo shortly after fertilisation. We will also study how these RNA molecules are packaged into the sperm as they develop and mature in the testis. Complementing these studies we will explore the cellular structure of the testes to determine how a poor quality diet affects the way they make sperm. Our second objective will study the composition of the seminal plasma and how it interacts with the sperm and the maternal reproductive tract. These interactions are important as the seminal plasma adds additional RNA molecules to the sperm after they leave the testes, preparing the sperm for fertilisation. Additionally, the seminal plasma initiates a range of immune and inflammatory responses within the uterus that prepares it ahead of embryo implantation. Therefore we will study how the seminal plasma modifies the RNA cargo of the sperm and how it affects the proteins, immune cells and blood vessels within the uterus. Following this, we will characterise the interaction between the uterus and the embryo to see if their normal communication is disrupted by poor paternal diet. Finally, we want to understand how quickly the sperm and seminal plasma can return to normal once the LPD and HFD males have been placed onto a control diet. These studies will be important for informing how permanent the effects of a poor quality diet might be for male reproductive health.This work is timely in its focus on the role of a father's diet. In addition, our focus on the role of the seminal plasma as well as the sperm means our study is also novel. We believe that understating how a father can affect the health of his offspring is critical for both informing men on how improve their chances of becoming a father and on the benefits for the health of their children.